Mach 5 derailleur cable routing

I'm wanting to replace the derailleur cables & housing and the Mach 5 has two sections that don't have housing. Thinking of drilling out the cable guides to accept full housing from shifter to derailleur? Have you done this and what are your thoughts?
I know they make guides you can attach to the guides on the frame but my thinking was if you run full housing, why would you want to go back?
Let me know if you have done this or not, and why.
Thanks

Is full length a necessity? If not, I wouldn't drill out the cable stops. Also, the front triangle is pretty tight on my medium mach5 and it would be a PITA to drill those out. And don't forget about resale value -- drilling those out would probably not be desirable for everyone.

So, after reading many threads on the interwebs and checking out all the new bikes at the LBS running full housing I did the conversion this afternoon.
It was a piece of cake and there really is no reason not to do this.
Shifting is really smooth and there isn't any open cable sections to attract dirt and water.
Tomorrow I'm changing the cables on my other bikes and running full housing too